first make a movie clip
1>create 3 key frames
2>on key frame one, make a text
3>copy your text and paste in place on layer 3
4>make on leyer 2 a neon box at the bigin of your text
5>make on all layers on frame 60 a key frame
6>on layer 2 frame 60 make the box larger tha the text
7>right click on leyer3 and click on mask
8>ctrl+enter and you got this